1540-35-8Relevant academic research and scientific papers
5,7-Bis(2′-arylethenyl)-6H-1,4-diazepine-2,3-dicarbonitriles: Synthesis, and experimental and theoretical evaluation of the effects of substituents at 5,6,7-positions on the molecular configuration and spectral properties
Tarakanov, Pavel A.,Simakov, Anton O.,Dzuban, Alexander V.,Shestov, Vladimir I.,Tarakanova, Ekaterina N.,Pushkarev, Victor E.,Tomilova, Larisa G.
, p. 1138 - 1146 (2016)
A series of novel 5,7-bis(2′-arylethenyl)-6H-1,4-diazepine-2,3-dicarbonitriles was synthesized through sequential aldol condensation reactions of 1,3-diketones with diaminomaleonitrile, and the resulting 5,7-dimethyl-6H-1,4-diazepines were condensed with aromatic aldehydes. The substituents' effects on the spectral properties and conformational states of the molecules in solution were studied using 2D NMR techniques and DFT calculations. Specific intramolecular steric interactions in derivatives substituted at the C6 position were discovered and investigated in detail. Differential scanning calorimetry and thermogravimetric analyses revealed the strong dependence of the thermal stability of the newly prepared diazepinodicarbonitriles on the nature of the substituents. This offers new insight into the structure-property relationships of arylethenyl-substituted diazepine derivatives.
Synthesis of valuable chiral intermediates by isolated ketoreductases: Application in the synthesis of α-alkyl-β-hydroxy ketones and 1,3-diols
Kalaitzakis, Dimitris,Rozzell, J. David,Smonou, Ioulia,Kambourakis, Spiros
, p. 1958 - 1969 (2007/10/03)
Regio- and stereoselective reductions of α-substituted 1,3-diketones to the corresponding β-keto alcohols or 1,3-diols by using commercially available ketoreductases (KREDs) are described. A number of α-monoalkyl- or dialkyl-substituted symmetrical as well as non-symmetrical diketones were reduced in high optical purities and chemical yields, in one or two enzymatic reduction steps. In most cases, two or even three out of the four possible diastereomers of α-alkyl-β-keto alcohols were synthesized by using different enzymes, and in two examples both ketones were reduced to the 1,3-diol. By replacing the α-alkyl substituent with the OAc group, 1-keto-2,3-diols, as well as 1,2,3-triols were synthesized in high optical purities. These enzymatic reactions provide a simple, highly stereoselective and quantitative method for the synthesis of different diastereomers of valuable chiral synthons from non-chiral, easily accessible 1,3-diketones.
Synthesis of substituted 3-cyano-2-pyridones: Part IV - Influence of 3-alkyl-2,4-pentanedione and N-alkyl cyanoacetamide structure on the enzyme catalyzed synthesis of substituted 3-cyano-2-pyridones
Mijin, Du?an ?.,Mili?, Branislav D.,Mi?i?-Vukovi?, Milica M.
, p. 993 - 1003 (2007/10/03)
Lipase from Candida rugosa has been used to study the influence of 3-alkyl-2,4-pentanedione and N-alkyl cyanoacetamide structure on the enzyme catalyzed reaction of pyridone ring formation in water at 40°C. Starting with 1,3-diketones and cyanoacetamides and for comparison, the expected corresponding substituted 3-cyano-2-pyridones have been synthesized by chemical methods. Bulkier substitueras lower the initial reaction rate of the enzyme catalyzed reactions and consequently the yield of the corresponding pyridones. N-alkyl cyanoacetamides are more reactive in comparison to the corresponding 3-alkyl-2,4-pentanediones with respect to the obtained yields of the corresponding substituted 3-cyano-2-pyridones.
Normal and abnormal heme biosynthesis. 1. Synthesis and metabolism of di- and monocarboxylic porphyrinogens related to coproporphyrinogen-III and harderoporphyrinogen: A model for the active site of coproporphyrinogen oxidase
Lash, Timothy D.,Mani, Ukti N.,Drinan, Martin A.,Zhen, Chun,Hall, Troii,Jones, Marjorie A.
, p. 464 - 477 (2007/10/03)
Coproporphyrinogen oxidase (copro'gen oxidase), which catalyses the conversion of coproporphyrinogen-III via a monovinylic intermediate to protoporphyrinogen-IX, is one of the least well understood enzymes in the heme biosynthetic pathway. To develop a model for the substrate recognition and binding recognition for this enzyme, a series of substrate analogues were prepared with two alkyl substituents on positions 13 and 17 in place of the usual propionate residues. Although the required substrate probes are porphyrinogens (hexahydroporphyrins), the corresponding porphyrin methyl esters were initially synthesized via a,c-biladiene intermediates. These were hydrolyzed and reduced with 3% sodium amalgam to give the unstable porphyrinogens needed for the biochemical investigations. These modified structures were metabolized by avian preparations of copro'gen oxidase to give monovinylic products, but the second propionate residue was not further metabolized. In three cases, the metabolites were isolated and further characterized by proton NMR spectroscopy and mass spectrometry. When methyl or ethyl groups were placed at the 13 and 17 positions, the resulting porphyrinogens were very good substrates (although the ethyl version, mesoporphyrinogen-VI, gave slightly better results), but when propyl units were introduced metabolism was significantly inhibited and the butyl- substituted structure was only slightly transformed after long incubation periods. These results suggest the presence of an active site lipophobic region near the catalytic site for copro'gen oxidase. The observation that the related 3-vinyl- and 3-ethylporphyrinogens with 13,17-diethyl substituents were not substrates for this enzyme confirmed the need for a second propionate residue to hold the substrate in place at the catalytic site.
Substituent Effects on the CC Bond Strength, 16. - Thermal Stability and Enthalpies of Formation of β-Dicarbonyl Compounds. - Stabilisation Enthalpies of α,α'-Diketoalkyl Radicals
Noelke, Margot,Verevkin, Sergej P.,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 41 - 52 (2007/10/02)
The geminal interactions of the two carbonyl groups in seven β-diketones of the type 8-9 and 11-13 were estimated from their enthalpies of formation, which were deduced from their heats of combustion and enthalpies of vaporization.The radical stabilisation enthalpies RSE of the α,α'-diketoalkyl radicals 9-13 were obtained from the enthalpies of activation ΔH(excit.) of thermal CC bond cleavage of eight model compounds of the type 9-13 by their comparison with ΔH(excit.) of comparable hydrocarbons of similar strain.For non-cyclic α,α'-diacylalkyl radicals and six-membered cyclic ones RSE = 54.8 +/- 1.3 kJ mol-1 was determined, which indicates an additive stabilisation by two carbonyl groups. - Key Words: Enthalpies of formation/ Geminal substituents, energetic interaction of/ Bond cleavage, C-C, kinetics of/ Radicals, stability of/ Increments, thermochemical/ Bond strength, substituent effects on
